Radio transmitting system



Oct. 24, 1933. F. GERTH ET AL 1,931,864

RADIO TRANSMITTING SYSTEM Filed May 10, 1930 Patented Oct. 24, 1933 nAnio TRANSMITTING SYSTEM Felix Gcrth, Berlin-Tempelhof, and Ernst Kramar, Eberswalde, near Berlin, Germany, assignorsto C.-Lorenz Aktiengesellschaft, Berlin- I V Tempelhof, Germany Application May '10, 1930, Serial No. 451,330,- in Germany June 6, 1929 and i 6-Claims. (o1. ze -17) Applications havebeen filed in Germany June 6, 1929; Austria April 7, 1930; The Netherlands April 16, 1930; and Italy April 16,1930.

In the art of transmitting directed rays by means of so-called sparking beacons, as is well known, two directing aerials or systems of aerials situated perpendicularly to one another are excited alternately in "such a manner, that the pause of the signals emitted by one aerial, is filled out by the signals transmitted bythe other antenna. Owing to the diagram of radiation of the directed transmitting apparatus there exist some lines in space, on which the signals of both systems of aerials are received with an'equally intense energy. Provided a suitable choice of the letters is made,- mostly the signals .and are selected, the signals will merge on said line of equal energy into a continuous dash, that is to say, the pauses'ofthe one, signal are filled out by the other signals;

But the occurrence of said continuous dash is dependent. on the condition, that the antennas are connected and disconnected at the same time without any'retardation. Tests made with the end in view to carry through such a switching by means of relay arrangements, have not been successful owing to the, periods of actuation required by the arrangement oftherelays. For that reason two main transmitting devices were alternately operated by a key together with a common vcontrolling transmitting I apparatus,

ed in series. One of these'choking coils is prelim-' inarily magnetized with an additional winding.

That circuit comprising the preliminarily magne-,

tized choking coil, will supply the high frequency energy to the, appurtenant system of directing aerials owing to the small inductive resistance of the choking coil. This preliminary magnetization is neutralized by the key winding provided thereon and simultaneously the other'one of the two choking'coils is magnetized,

since both the key windings are connected in series. Owing to this fact new high frequency energy is supplied to that system of aerials, which 1 did not transmit, while the other system of aerials which did transmit up to that time, is not supplied with energy. i

The subject matter of the invention will be more clearly understood with the aid of the accompanying drawing, in which Figure l-is a diagrammatic view of the arrangement'according to the invention, and

Figures 2a and 2b arediagrammatic views of the direct current windings of the choking coils.

The high frequency energy is supplied from the transmitting apparatus to thekey-instrument by way of the inductance L1. An additional inductance L2 is coupled with L1 to which two circuits are connected, which are each in connection "with a directing system. It is immaterial here, whether'a'single directing aerial is concerned or a voluminous system of direct: ingaerials. One of the branches (I) is formed by L2, the capacity C1, the inductance L3 (C1 and 1e are arranged for tuning purposes), L4, 02, L6 and the winding W1 of the choking coil DTl. The other branch (II) consists of the elements L2, C1,'L3, Ls, .Cs, Ls and'WQ. The inclusion TEs AT N -i FF of condensers C2 and C3 in the'respective parts of the circuits I and 11 individual thereto en able the such parts to be separately tuned and thus improve the operation of the system. The systems of aerials are coupled withthe inductivities L4 and Lsby. way of L1 and L8. 'The choking coils are provided with iron cores, upon which additional windings are wound; Both the key; windings W3 and W4 on the choking coil DTl and DTz respectively are connected in series by the interposition of the key T, which in a given case may at the same time be utilized for transmitting'the signals, and in the circuit of said device is situated the source B of direct current. The choking coil D72 in addition is provided with a permanent magnetizing winding W5, which is directly connected withthe battery B through the interposition of a regulating resistance. The

mode of action of the arrangement is as follows. If the key T is open, the choking coil DT2 is preliminarily magnetized by means of the permanent magnetizing winding W5, that is to say, in consequence of the small inductive resistance of the choking coil Drz the high frequency energy emitted by the transmitting device is supplied through'the circuit II to the system of aerials connected at L8. The system of aerials connected at L7 receives no energy at that moment, since the choking coil DH is under no preliminary magnetization. As' soon as the key T is depressed a direct current will flow through the windings W3 and W4. Bythis means the choking coil Dn is magnetized and the transfer of high frequency energy is, effected by the circuit I, since at the same time the permanent magnetizing current in the choking coil Drz gener- 1 coil will'remain active.

ated by W5 is compensated by the winding W4.

The windings of thechoking coils must beparticularly adapted for that purpose.

' The direct current windings of the' choking coils are againrepresented in .Figure' 2. The choking coil DTriS illustrated in Figure 2a. Upon the iron core E1 are arranged two windings, through which direct current will flow. The high frequency windings are not shown in the drawing for the sake of clearness. In order to maintain the heating of the key choking coils caused by the direct current in the various windings and the fluctuations of the direct' current caused thereby in both choking coils at a constant value,

according to a further-feature of the inventionalso the choking coil DH is provided with a compensating winding consisting of two halves,

which are differentially connected, so that, while the winding produces a, heating effect, its net magnetic effect upon the core is nil. Forthat purpose an additional winding We is mounted on the shanks besides the key winding W3 proper, which normally is secured to the iron core E1. WindingSWG and Waare'wound in the same direction'on'the left shank of thecore E1 and in the opposite direction on the right shank, as

shown in Fig. 2. 'On account of this arrangement the magnetizations caused by the winding We are' compensated in the iron core, so that only the key winding-W3 proper of the choking In the choking coil Drz illustrated in Figure 2b the keywinding W4 and the permanent magnetizing winding W5 are rhountedinsucl'i a manner, that'during theflow of direct current through the key winding W4 5 the magnetization of both windings: will be compensated. -=The arrowsof current shown in' the drawing indicate the instant at which the choking coil will be key-operated, so that the circuit II will not supply any. current to the system of aerials connected at Ls.

If the circuits I and II are tuned between the points of their connection, that is tosay those parts of the circuits, which are not formed in common by L2, C1, L3 by means of condensers C2 and C3 respectively to the frequency supplied,

there obtains at the chokingcoils, the least possible voltage, which-correspondsto the value of prising a keying device so inductively coupled to said coupling circuits thatupon closure or openingof the contact of said device the impedances of said coupling circuits are varied oppositely.

2,-A radio transmitting system according to energy.

claim 1, characterized in this that each circuit contains a' choke coil having a core, and said means includes a winding on one choke coil core connected in circuit with a source of direct current, a winding on each choke coil core connected in series, and a circuit closer to close circuit from said source of direct current through the serially connected windings in a direction whereby said two windings on the same core are rendered differential in their effect upon said core.

' 3. A radio transmitting system comprising two antennaaa source of radio frequency, a coupling circuit for each antenna coupling, it to said source, a choke coil having a core for each coupling circuit having a winding thereon, one of the choke core coils having a second winding connected in circuit with a source of direct current and a third winding connected to said direct current source and differentially with respect to said second winding, and said other choke core coil having a second winding connected in series with said third winding, and a circuit closer arranged to open and close circuit from said direct current source through said serially connected windings.

4. A radio transmitting system comprising two antennae, a source of radio frequency energy, coupling circuits between said source and said antenna, and means to render said coupling circuits alternatively effective to transfer energy to either of said antennae before effective transfer of energy to the other is interrupted, said means comprising a keying device so inductively coupled to the said coupling circuits that upon operation thereof the impedance of one circuit is increased whilst that of the other isdecreased,

5. In a radio transmitting system comprising two antennae, a source of radio frequency energy, coupling circuits between said source and said antennae which normally prevent the radio fre quency energy from being simultaneously and effectively transferred to said antennae, and means to render said coupling circuits alternatively effective to transfer energy to one or the other of said antenna, said means comprising a keying device so inductively coupled to said coupling circuits that upon closure of the contact of said device the impedance of one coupling circuit is decreased whilst the impedance of the other coupling circuit is increased.

6. A radio'transmitting system comprising two antenna, a source of radio frequency energy, coupling, circuits between said source and said antennae, each coupling circuit being formed by a path individual thereto and a path common to the two circuits and each path containing inductance and capacity tunable to the frequency of said source, and means to render said coupling circuits alternately effective to transfer energy to one or the other of said antennae, said means comprising a keying device so inductively coupled to said individual paths that upon the opening of the contact of said device one coupling circuit is rendered operative for transfer of energy whilst simultaneously the other coupling circuit is rendered efiectively' inoperative for transfer of FELIX GERTH. ERNST KRAMAR. 

